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Application and Design
The WD-400 series are non-motorized backdraft dampers which may be mounted either vertically for intake air or mounted
horizontally to allow vertical airflow down and prevent reverse airflow. The dampers are opened by air pressure differential and
closed by springs. Optional motor packs are not available.
Ratings (See page 2 for specific limitations)
Pressure: 2.0 in. wg (498 Pa) - differential
pressure
Velocity: 2500 fpm (13 m/s)
Temperature: 180°F (82ºC)
Standard Construction
Frame: 18 ga. (1.3mm) galvanized steel
Blades: 0.025 in. (0.64mm) aluminum
Axles:
3
/16 in. (4.8mm) dia. zinc plated steel
rod, full length
Bearings: Synthetic (acetal)
Linkage: 0.064 in. (1.6mm) 6061T6 aluminum
tie bar
Blade Seals: Vinyl
Size Limitations (see pages 3 & 4 for specific
limitations)
Minimum Panel Size
8 in. W x 8 in. H
(203mm x 203mm)
Maximum Panel Size
Single Panel: 31 in. W x 74 in. H
(787mm x 1880mm)
Double Panel (WD-400/410): 50 in. W x 74 in. H
(1270mm x 1880mm)
Double Panel (WD-420/430): 63 in. W x 74 in. H
(1600mm x 1880mm)
Triple Panel (WD-420/430): 74 in. W x 74 in. H
(1880mm x 1880mm)
Options and Accessories (at additional cost)
• 1
1
/2 in. (38mm) flange on discharge: WD-420
• 1
1
/2 in. (38mm) flange on intake: WD-430
• Stainless Steel Axles
Airflow
*H
Model WD-400
No Flange
Airflow
*H
Model WD-430
Flange on Intake
Airflow
*H
Model WD-420
Flange on Discharge
Airflow
*H
Model WD-410
No Flange
1
1
/
2
in
.
4
5
/
8
in
.
M
a
x.
3
3
/
8
in
.
4
5
/
8
in
.
M
a
x.
3
1
/
2
in
.
4
5
/
8
in
.
Max.
3
1
/
2
in
.
1
1
/
2
in
.
1
1
/
2
in
.
1
1
/
2
in
.
3
3
/
8
in
.
3
3
/
4
in
.
Max.
H*
W*
Triple Panel
Double Panel
Single Panel
H*
H*
W*
W*
WD-400 SERIES
Non-Motorized Backdraft Damper
Horizontal or Vertical Mount (Intake)
*W & H dimensions furnished
approximately
1
/8 in. (3mm) under size.